Thermostatic device



Jan. 2, 1940. w, 5, uano JR 2,185,436

THERMDSTATIC DEVICE Filed Feb. 19, 1957 Patented Jan. 2, 1-940 2,185,436 THERMOSTATIC DEVICE William Gordon,

Jr., North Tonawanda, N. Y.,

assignor to Roberts-Gordon Appliance Corporation, Buffalo, N. Y.

Application February 19, 1937, Serial No. 126,688

7 Claims.

This invention relates to improvements in thermostatic devices, and of this kind which may be used in with a pilot flame of One of the objects vide a thermostatic particularly to devices connection a fluid fuel burner.

of this invention is to prodevice of this kind of improved and simplified construction, which will respond differently to the action of heat from an adjacent pilot flame than to the heat of the main burner of a furnace or heater. It is also an object of this invention to provide a thermostat which operates more quickly in response to changes in temperature than thermostats heretofore commonly employed. invention is to provide a this kind with improved means the movement of. the

Another object of this thermostatic device of for amplifying thermostatic element and transmitting the amplified movement to a movable part. A further object is to provide an improved mounting for a thermostat and a burner or source of heat acting upon the thermostat.

Other objects of this invention will appear from the following description and claims.

In the accompanying drawing:

Fig. 1 is a sectional elevation of a pilot burner and a thermostatic device embodying this invention, together with fuel valve and connections for a diagrammatic view of a actuating the same by means of said thermostatic device.

Fig. 2 is a fragmentary sectional elevation similar to Fig. 1, but showing parts of the thermostatic device in a different position.

-Fig. 3 is a side elevaton thereof.

Fig. 4.

is a front elevation thereof.

The thermostat and pilot burner may be arranged in proper relation to each other and to a main burner in any suitable or desired manner. In the particular construction shown, the thermostat and pilot burner are a frame or supportin both mounted upon g member I, which may include a box or channel-shaped portion 8 having an outwardly extending projection 9 on which a pilot burner I is mounted. The projection 9 is apertured and the lower end thereof is provided with a threaded hole adapted to receive a coupling member H l2 may be suitably ner.

11 through which charged into a passa to which a gas supply pipe connected in any desired man- The coupling member H has an aperture gas or other fuel may be disge l formed in the projection H of the housing, and this projection is also provided with a lateral aperture or conduit l6 formed therein and terminating within the boxlike structure 8. Air

for mixing with the gas disupwardly through the passage l5 into the burner tube lo, the mixture of air and gas discharged 5 from the burner It being further mixed with secondary air which may pass to the flame at the discharge end of the pilot burner tube Ill. The burner tube l0 may have a threaded engagement in the upward passage l5 and may be secured in place by means of a lock nut I8. In case, the main burner is located at some distance above the pilot burner 10, a guide tube 20 for the pilot flame may be provided to guide the pilot flame to the main burner. The pilot burner herein de- 15 scribed is of itself not a part of this invention, and it will be obvious that my improved thermostatic device may cooperate with burners of. any other suitable or desired construction.

One of the walls of the box-like frame mem her 8 terminates at 22 and at the upper end of this wall, my improved thermostat may be secured. This thermostat is formed of two elements, which in the construction shown are in the form of strips of metal 24 and 25. These elements are spaced apart throughout the greater 25 part of their length, those shown in the drawing being arranged in approximately parallel relation to each other. The opposite ends of these elements are rigidly secured together. These elements are made of materials having the same or very similar thermal expansion characteristics, so that when subjected to the same temperatures, both elements will expand substantially to the same extent, and consequently, both elements may be made of the same material. In the particular embodiment of my invention shown in the drawing, the thermostat is formed of a single piece of, strip metal, such for example as a piece of steel, which is bent at its middle portion at 26 in such a manner that the two halves of the strip lie approximately parallel to each other and form the strips 24 and 25 of the thermostat. In this manner, the lower ends of the strips 24 and 25 are integrally secured to each other, and the other ends of the two strips may be secured to each other in any suitable or desired manner. For example, in the construction illustrated, I have shown the upper ends of the two strips 24 and 25 as welded together at 21. One end of the thermostat, for example the lower end, may be secured to a fixed support, such as the housing or frame member 1, in any suitable manner, for example, by means of. a screw 29 extending through a hole in the thermostatic member and engaging the wall 22 of the box-like structure 8. The two strips 24 and 25 are separated from each other so that heat will not be readily conducted from one strip to the other, and if desired, a layer of asbestos or other heat may be arranged between the two strips 24 and 25. It will be understood, however, that insulating material is not necessary since even a small air space between the two metal strips 24 and 25 is sufficient to resist the ready transfer of heat from one strip to the other.

The thermostatic device is so arranged with relation to the pilot flame that one of the thermostatic elements is more exposed to the heat of this flame than the other element. As shown, the element 24 faces the pilot flame while the other element 25 faces away from the. pilot flame in such a manner that the thermostatic element nearest to the pilot flame shields the other element from the heat of the flame. In order to expose the thermostat to the heat of the pilot flame, the pilot burner Ill may be provided at the srde thereof nearest to the thermostatic device with a slit 32, through which some of the mixture of air and gas may.pass to form-a flame on the exterior of the burner tube It). The guide tube 20 is also provided with a slit or opening 33, through which secondary air may pass to support combustion of the primary air and gas mixture within the tube, and through which the heat of the pilot flame may pass to the thermostatic element 24. In the particular construction shown, the slit 33 in the guide tube 20 is preferably of a partly spiral form and the upper end of the tube 20 may be bent over, as shown at 34, to deflect the flame toward the main burner (not shown). I

As a result of the construction described, it will be obvious that when the pilot flame is burning, the heat of the flame will result in rapid heating of the element 24 of the thermostat, and in expansion of the same to a materially greater extent than the element 25, which, of course, receives a lesser amount of heat from the pilot flame. As a result of this unequal heating of the two elements, unequal expansion of the same results, so that the thermostatic device warps or bends away from the pilot bumer, as clearly shown in Fig. 2, and this motion of the thermostatic device may be employed in any suitable manner for transmitting motion to any suitable control or alarm device.

In view of the fact that both of the thermostatic elements 24 and 25 are of the sameor similar metal, it follows that movement of the thermostatic element results only when there is a difference in the temperature of the two elements of the thermostat. In ordinary bi-metallic thermostats, a certain movement of the thermostatic element results, which is proportional to the temperature of the thermostatic element.

Consequently, if after the pilot flame goes out, the-supply of fuel to the By means of the construction herein main burner until the thermostatic device becomes cooled, thus resulting in the danger of explosions or other damage from the escaping fuel. disclosed, this source of danger is eliminated, since if the pilot flame should become extinguished while the main burner is on, the element 24 will no longer be subjected to greater heat than the element 25, and consequently, the two thermostatic elements will soon acquire the quently, after the supply of fuel to the main burner is interrupted, the same cannot be'again turned on until after the pilot burner is lit.

Any suitable or desired means may be employed alarm 'means. In the particular construction shown for this purpose, I have provided a relatively long arm 35, the upper end of which may be welded, or otherwise rigidly secured to the upper end of the thermostatic device, for. example, to the upper end of the thermostatic element 25.

arranged to engage the end of a slidable rod 31 arranged in a guide tube 38. To the end of the rod 3'! is secured a knob or enlargement 39 of 40 and 43 may be connected by conductors 45 and 45 to a source of power 47 and to an electric solenoid or motor 48 for openinga valve 49 in a fuel supply pipe 50. This valve may be of the utilizing the movement of the thermostatic device may, shown.

The channel-shaped portion 8 of the frame member 1 may have its open side or face closed in any suitable manner, and in the construction shown, a sheet metal cover or closure member 52 is employed which may be secured by means of course, be employed in place of that of screws 53 and 54 to the box-like part 8 of the supporting member of the thermostat. It will be noted that the lower end of this box-like member is left partly open, so that cool air from below the burner may pass upwardly in the channel-shaped or box-like part 8 of the supporting member of the thermostatic device, to supply primary air through the passage IE to the pilot burner and also air will pass upwardly to the flame through the open upper end of the supporting member in contact with the thermostatic element 25, thus resulting in removing heat from this element, so that no matter how long the pilot flame may be burning, a difference in temperatures will be maintained between the elements 24 and 25 of the thermostat. It will also be noted that the thermostatic elements 24 and 25, as shown in Fig. 2, tend to warp or bend away from the pilot flame, as the element 24 becomes heated, so that when the pilot flame is lit, the element 24 will be initially subjected to greater heat from the pilot flame than after preliminary heating of this element. This helps to increase the speed with which the thermostatic device operates. By arranging the thermostatic elements 24 and 25 close to each other and in heat conducting relation to each other at their ends, the two elements will rapidly attain the same temperature when the pilot flame is extinguished. This results in rapid action of the thermostatic device when the pilot flame becomes extinguished.

The device described has the advantages that the thermostatic elements may be made of strips of steel or other inexpensive material having higher heat resisting properties than the metals of the bi-metallic thermostats heretofore commonly used. The thermostatic elements also are of greater strength than the usual bi-metalli'c elements, so that a much greater force is exerted when these elements warp or bend out of their normal positions. By means of the arm 35 herein described, which is rigidly or integrally connected with the thermostat, a very eflicient and inexpensive amplifying or enlarging of the move ment of the thermostatic device is effected. The thermostatic device and its movement amplifying means are, consequently, of unitary or one piece structure, thus eliminating any pivots or fulcrums such as are commonly employed to amplify themovement of a thermostat and which are subject to wear and to rapid deterioration when exposed to heat and which introduce friction in the transmission of movement from the thermostat to the part actuated thereby.

The thermostatic device described also has the advantage that the movement amplifying member or arm 35, in the construction illustrated, is arranged in the air conducting passage or channel of the frame member, so that any tendency of this arm to become heated because of its connection with the thermostat is counteracted by the flow of cool air in the channel.

In the operation of my improved thermostat, it will be noted that when the heat of the main burner has raised the temperature of the two elements to a certain extent, a relatively small difference in temperatures will be maintained by the pilot flame between the elements 24 and 25. Consequently, if the pilot flame becomes extinguished, the two elements will very rapidly attain the same temperatures, which in turn results in a rapid action of the thermostat to turn off the fuel supply to the main burner. Furthermore, if for some reason the main burner generates an excessive amount of heat, both elements of the thermostat will become heated to approximately the same temperature, and the thermostat will act to turn of! the supply of fuel to the main burner and thus avoid danger incident to overheating of the furnace or heater..

I claim as my invention: 1. A thermostatic device including a support,

5 a burner mounted on said support, a thermostat comprising a pair of strips of similar metal having their opposite ends rigidly secured to each other -and having one of the ends of said strips secured to said support with one of said strips facing said burner and positioned between said burner and the other strip to. shield said other strip from the heat of said burner, means for directing a current of cooling air to said other strip to dissipate heat therefrom, and means connected with the'other end of said strips for transmitting movement of said other end when said strip facing said burner becomes heated to a greater extent than said other strip.

2. A thermostatic device including a support having an air passage therein, a burner mounted on said support, a thermostatic device including a pair of strips of similar metal extending substantially parallel to said burner with one of said strips facing said burner and interposed between said burner and said other strip to shield said other strip against the heat of the burner, the

intermediate portion of said strips being spaced apart, means for securing one end of said two connected strips to said support at one side of said air passage therein, whereby cool air flowing in said passage will act on said other strip, and means connecting with the'other end of said connected strips to transmit movement of said strips when said strip facing said burner becomes heated'to a greater extent than said other strip.

3. A thermostatic device including a support having an air passage therein, a burner mounted on said support, a thermostatic device including a pair of strips of similar metal extending substantially parallel to said burner with one of said strips arranged closer to said burner than said other strip, means for securing one end of said connected strips to said support, said air passage conducting cool air into contact with said other strip, and means connected to the other end of said connected strips for transmitting movement of said end of said strips when said strip adjacent to said burner becomes heated to a greater extent than said other strip.

4. A thermostatic device including a support having an air passage therein, a burner mounted on said support, a thermostatic device including a pair of strips of similar metal extending substantially parallel to said burner with one of said strips arranged closer to said burner than said other strip, means for securing one end of said connected strips to said support, said air passage having a branch conducting air to said burner and another branch conducting air into contact with said other strip for cooling the same, and means connected with the other end of said connected elements for transmitting motion resulting from the heating of said strip adjacent to said burner to a greater extent than said other strip.

5. A thermostatic device including a support having an air passage therein, a burner mounted on said support, a thermostatic device including a pair of strips of similar metal extending substantially parallel to said burner with one of said strips arranged closer to said burner than said other strip, means for securing one end of said go for transmitting connected strips to said support, an arm secured to the other end or -said connected strips and oi. greateniength than gither 01' said strips for transmitting and amplifying movement 01' said other end of said strips, said arm being arranged in said air passage, said air passage conducting cool air to said other'strip and cooling said arm.

6. A thermostatic device including'a support .having an air passage therein, a burner mounted strips when said strip adjacent to said burner becomes heated to a greater extent than said other strip.

7. A thermostatic device including a support, a thermostat comprising a pair of strips of similar metal having their opposite ends rigidly secured to each other and having one of the ends of said strips secured to said support, a burner arranged adjacent to said thermostat with one of said strips 01' the thermostat i'acing said burner and positioned between said burner and the other strip to shield said other strip from the heat 01' said burner, means for directing a current oi. cooling air to said other strip to dissipate heat therefrom, and means operated by the other end of said strips for transmitting movement 01 said other end when said strip facing said burner becomes heated to a greater extent than said other s rip.

WILLIAM B. GORDON, Ja. 

